Gimbal clamping device



June 12, 1951 D. w. BLAIR EIAL 2,556,253

GIMBAL CLAMPING DEVICE Filed June 10; 1949 AGENT.

As will be apparent to workers in the art, the frame I0, together with any mechanism contained therein, constitutes a mass suspended from a gimbal. The center of gravity of this mass is preferably arranged well below the radial center I2 of ring II so that gravitational pull will automaticaly tend to align the former in a vertical line below the latter. For reasons'which will become apparent, trunnion bearings I3 and I4 are preferably self-aligning ball bearings of wellknown construction and completely encircle the corresponding trunnion pivots so that the latter are held firmly against movement out of ring II or frame I5.

In accordance with the present invention there is affixed to frame member I0, and preferably to the bottom thereof, a concaved member I8 having a concaved surface I9 directed outwardly from frame I0. Member I8 may be a dish-like element affixed to frame Ill by a plurality of support elements 28 as shown in Fig. 1, or member I8 may be an equivalent solid block having a suitably concaved recess such as is shown in Figs. 4 and 5. Concaved surface I8 is preferably conical in form and has a central vertex or a conical apex 2|. However, as will be explained more fully hereinafter, surface I9 may be concaved to conform to a wide variety of other shapes.

For illustrative purposes in the drawing of Fig. 1, it has been assumed thatthe center of gravity of the gimbal suspended mass, includin frame I0, is at the geometric center of frame I0. It has been assumed also that the device shown therein has been arranged in a preselected normal position such that base I! is in a horizontal plane. With these assumptions in mind, it will be seen that the center of gravity of the mass is directly below the center I2 of gimbal ring I I on the vertical axis passing therethrough. The vertex 2| of concaved member I8 is preferably coincident with this axis, although it may be otherwise arranged for other preselected normal positions of the device as will be apparent to skilled workers in the art.

Aligned longitudinally on a straight line or axis passing through vertex 2| and center I2 is a movable convex member 22 adapted to be moved into and out of contact with surface I9 and to come to rest at vertex 2| which is the highest, 1. e. the most recessed, point on surface I8. In a preferred embodiment, as illustrated in Figs. 1 and 2, convex member 22 is a screw threaded shaft having a sphere 23 mounted upon the end thereof by retainer ring 24. Sphere 23 is free to rotate in any direction Within retainer ring 24 and thereby provides an anti-friction contact with surface I9. Shaft 22 is mounted for longitudinal movement into and out of a gear box 25. Within gear box 25 are suitable gears for turning, at low speed, a nut (not shown) screw threadedly engaged upon shaft 22. Gear box 25 is secured to a suitable part of frame member I5, such as base H. A shaft 26 having a spring loaded clutch 21 therein may connect gear box 25 to a suitable reversible motor 28. By operating motor 28 in the proper direction member 22 advances toward and/ or along surface I9 until member 23 reaches vertex 2| whereupon further advance is halted, causing clutch 21 to slip. When motor 28 is operated in the reverse direction, members 22 and 23 are drawn away from vertex 2| and surface I9.

Turning now to Figure 2, let it be assumed that the device of Fig. 1 is set in other than the preselected normal position as, for example, in a position such that base I1 is in a plane slightly inclined from horizontal. It will be seen that, as member 22 is slowly retracted into gear box 25, anti-friction member 23 is drawn downward and slides along surface I9 permitting the center of gravity of mass ID to move slowly into a position vertically beneath the center I2 of ring II. Since mass I8 is not suddenly released, it is not free to swing as a pendulum but its movement is clamped, thereby causing the mass to come to rest quickly. By employing self-aligning ball bearings in trunnions I3 and I 4, friction in these bearings is reduced to a tolerable minimum and mass I0 is free to assume an accurate equilibrium position. When it is desired to clamp the gimbal supported mass I0 while the latter is in a position such as is illustrated in Fig. 2, the motor 28 is operated in a proper direction to advance antifriction member 23 against surface I9. Member 23 then slides along surface I9 from the particular point of contact toward and into the vertex 2 I. Thereupon frame I0 is clamped against movement with respect to frame I5.

Motor 28 may be any suitable type of reversible motor. Preferably it may be a reversible electric motor which is connected by means of conductors 29 to a reversing switch 38 and a source of power, such as a battery 3|. It will be apparent that conductors 29 may be of any desired length and, accordingly, that the driving means, including gear box 25, shaft 26, clutch 21 and motor 28, is controllable from a remote distance.

Concaved member I8 may be constructed from any suitable material such as wood, solid resin, or metal. In accordance with a preferred form of our invention, member I8 is constructed from an electrically conducting material and is secured to frame II] by means of electrically insulating members 20. Gear box 25, shaft 22, and anti-friction contact member 23 are, likewise, constructed from electrically conducting material. A conductor 32 is electrically connected to member I8 and another conductor 33 is electrically connected to gear box 25. Conductors 32 and 33 are, in turn, also connected to a battery or other source of electrical power 34 and a current indicator 35 arranged in series. Members I8 and 23 thereby comprise switch contacts in the electrical circuit. It will be seen that, when member 23 is in contact with member I8, electric current may flow through indicator 35 thereby warning an operator at a remote distance that frame In is not free to move in the gimbal. However, when member 23 is not in contact with member I8, no current flows through indicator 35 and the operator can readily determine that frame II] is free to move in the gimbal.

Although, in the foregoing description, concaved member I8, shaft 22 and gear box 25 have been described as mounted below frame Ill, it will be apparent that these members may also be mounted above frame I0. Also, if desired, a cover 36 may be provided for totally encasing frame In, gimbal II, trunnion support member I5, legs I6, concaved member I8, and the driving means including gear box 25 and motor 28.

As mentioned earlier herein, concaved member I8 may be other than a dish-like member and may also have a concaved surface which is other than conical. It will be apparent, also, that means other than the screw-threaded shaft 22 may be employed to move the member 23 into contact with member I8 and surface I9.

Turning now to Fig. 4, another embodiment of a clamping device employing a rack and pinion in place of screw-threaded shaft 22 and a solid concaved member in place of the dish-like concaved member I8 is shown in accordance with our invention. In the drawing of Fig. 4, the numeral I8 designates a solid concaved member having a conically recessed surface I9. Member I8 may be secured directly to inner frame II) or may be electrically insulated therefrom on insulating pillars 20. As in the embodiment of Fig. 1, concaved member I8 is provided with a central vertex 2!. A conical convex member 23, having an outer surface adapted to mate with the surface I9, is arranged upon a shaft 22' and is adapted to be moved into and out of contact with surface I9. Shaft 22 is slidably mounted in a gear case 25. In the embodiment of Fig. 4, shaft 22 may be provided with a rack 31 adapted to be moved by pinion 38 secured to a shaft 26 journaled upon suitable bearings in gear case 25. As in the embodiment of Fig. 1, shaft 26 may be driven by clutch 2'! and motor 28. Preferably, however, speed reduction gears are interposed on shaft 26 between motor 28 and pinion 38. If desired, a manually operated lever or crank may be used in place of motor 28 to drive shaft 26.

Still another embodiment of a clamping device in accordance with our invention is shown in elevation, and partly in section, in Fig. 5. In this embodiment, a solid concaved member I8" is secured to inner frame member I8, either directly or by means of pillars 26. Member I8 is provided with an arcuately concaved surface I9". Preferably the central vertex of surface I9 may be specially recessed as shown at 2I" to receive anti-fraction convex member 23 when the latter is in clamping position. Anti-friction convex member 23 may be a sphere retained upon the end of shaft 22" by retainer ring 24 as in the embodiment of Fig. 1. Shaft 22" is slidably mounted for longitudinal movement in case 25" housing an eccentric cam 39 on shaft 26. A helical spring 40 surrounding shaft 22" within case 25" urges the shaft and contact member 23 out of contact with surface I9" and maintains contact between shaft 22" and cam 39. As in the embodiment of Fig. 4, driven shaft 26 is suitably journaled in bearings in case 25 and is preferably driven at low speed through a gear reduction train interposed along the shaft between cam 39 and motor 28.

It will be apparent to workers in the art that the best shape and dimensions of concaved surface I9 will depend upon the distance thereof from the center I2 of gimbal ring II and the angle through which frame II] is permitted to swing from its predetermined normal position. In any case, member I8 should be of such dimensions that convex member 23 may always be brought into sliding contact with surface I9.

' Surface I9 also should be so shaped and arranged with'respect to member 23 that the vertex 2|, i. e. the most recessed portion of surface I9, is aligned along a desired axis preferably passing through center I2 and the center of gravity of frame I0 and any mass contained therein.

While our invention has been illustrated by a single shaft 22 adapted to move a convex member 23 into sliding and seating contact with a concaved surface I9, it will be apparent that shaft 22 may be replaced by a plurality of shafts acting simultaneously to move convex member 23 into contact with surface I9.

Having fully described and illustrated our invention, what we claim and wish to secure by Letters Patent is:

1. A device for clamping gimbal leveled apparatus comprising, in combination, an outer frame member having a gimbal ring journaled for rotation therein, an inner frame member journaled for rotation in said ring with the center of gravity thereof below the center, of said ring, a member having a concaved surface and a central vertex therein secured to said inner frame with said concaved surface directed outwardly therefrom, a movable convex member interposed in a space provided between said surface and said outer frame and arranged for movement along an axis defined by a straight line passing jlhrough the center of said ring and said vertex when the latter is in a preselected normal position, and driving means secured to said outer frame and arranged for moving the convex member into and out of clamping contact with said concaved surface.

2. A device for clamping gimbal leveled apparatus comprising, in combination, an outer frame member having a gimbal ring jo'urnaled for rotation therein, a mass comprising an inner frame member journaled for rotation in said ring with the center of gravity of said mass arranged a substantial distance below the center of said ring, a member having a concaved surface and a central vertex therein secured to said inner frame with the concaved surface directed outwardly therefrom, a longitudinally movable shaft arranged in a space provided between said surface and said outer frame, the longitudinal axis of said shaft being aligned for movement along an axis defined by a straight line passing through the center of said ring and said vertex when the latter is in a preselected normal position, and driving means mounted upon said outer frame arranged for moving said shaft into and out of contact with said concaved surface and said vertex.

3. A device in accordance with claim 2 wherein the axis defined by said straight line passes substantially through the center of gravity of said mass, said concaved member is secured to the under side of said inner frame member, and the upper end of said shaft is provided with antifriction means for contact with said concaved surface whereby oscillation of said mass is damped during slow movement of the shaft out of said vertex.

4. A device in accordance with claim 2 wherein said driving means includes a motor and clutch and is controllable from a remote distance.

DONALD W. BLAIR. ADELBERT BARRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,104,892 Heusser July" 28, 1914 1,858,384 Andre May 17, 1932 2,192,905 Gattoni Mar. 12, 1940 2,357,822 Hasbrook Sept. 12, 1944 2,358,980 Kent Sept. 26, 1944 2,383,966 Hasbrook Sept. 4, 1945 FOREIGN PATENTS Number Country Date 692,754 Germany June 26, 1940 

